Waymo has a rather sizable advantage in the self-driving field. An order for “thousands” of more cars was announced yesterday, as the Alphabet division plans to soon launch a public ride service in Arizona. That lead is backed up by stats, with a report from the California Department of Motor Vehicles (DMV) noting the lowest disengagement rate among competitors.

The California DMV requires companies to submit statistics on when human drivers have to take manual control from a vehicle in autonomous mode to avoid an accident. In its report, Waymo notes that it sets “disengagement thresholds conservatively for our public road testing.”

“The vast majority of disengagements are not related to safety. Our test drivers routinely transition into and out of autonomous mode many times throughout the day, and the self-driving vehicle’s computer hands over control to the driver in many situations that do not involve a failure of the autonomous technology and do not require an immediate takeover of control by the driver.”

From December 2016 to November 2017, the Alphabet division reported 63 disengagements over the course of 352,545 miles driven in California with 75 vehicles. For comparison, as of November, Waymo’s vehicles have traveled 4 million miles in total.

Save for December and April, monthly disengagements are numbered in the single digits. Meanwhile, in November, Waymo impressively only had to disengage once over the course of 30,517 miles.

Other charts break down the cause of the disengagement, as well as the location. In the latter, most cars had to be controlled when driving on surface streets.

This is roughly over .18 disengagements per 1,000 miles. As The Information’s Amir Efrati compiled, Waymo has the lowest rate with GM-backed competitor Cruise coming in next at .8 disengagements on only 125,000 miles.

My quick tally on “disengagements” (humans taking over to avoid accidents) per 1,000 miles by self-driving car prototypes in California. pic.twitter.com/2TVItyk4r9